1. Field of the Invention
This invention relates to a method of determining abnormality of nozzles in an imaging (drawing) device using a liquid droplet ejection (or discharge) head having a plurality of ejection (or discharge) nozzles as represented by an ink jet head; an imaging apparatus; an electrooptic device; a method of manufacturing the electrooptic device; and an electronic equipment.
2. Description of the Related Art
An ink jet head (a liquid droplet ejection head) of an ink jet printer can accurately eject dot-shaped minute ink droplets (liquid droplets). Thus, by using a function liquid (hereinafter referred to as function liquid) such as a particular ink or photosensitive resin, for example, as an ejected liquid, the ink jet head is expected to be applied to a field of manufacturing of various devices.
For example, it is considered to manufacture a color filter of a liquid crystal display, an organic electroluminescence (EL) display and the like by using a head unit including a plurality of liquid droplet ejection heads. Specifically, the color filter is manufactured by ejecting function liquid toward a workpiece, such as a substrate of the color filter, from respective ejection nozzles of the respective liquid droplet ejection heads while moving the head unit relatively to the workpiece in two scanning directions orthogonal to each other.
Here, if an imaging operation is halted for a certain amount of time to perform loading/unloading of the workpiece and the like, clogging of the ejection nozzles may be caused by increased viscosity of the function liquid of the liquid droplet ejection heads. Thus, it is desired to dispose maintenance means for the liquid droplet ejection heads in an imaging apparatus and to perform maintenance operations, such as a preliminary ejection for ejecting the function liquid from the ejection nozzles and removal of the function liquid from the ejection nozzles by suction, by moving the head unit to a position where the maintenance means is disposed during the pause.
Moreover, in order to prevent defective products, it is also desired to confirm whether or not the function liquid is normally ejected from the respective ejection nozzles before starting the imaging operation after the maintenance operation.
Regarding a regular ink jet printer including no maintenance means, liquid droplet detection means is conventionally known, which includes an emitting element and a light receiving element and detects ejection of a function liquid based on a change in an amount of light received when the function liquid crosses an optical path between the two elements.
Also in the foregoing imaging apparatus, it is considered that, by using the liquid droplet detection means as described above, an ejection confirming operation for the function liquid is performed to determine whether or not the function liquid is normally ejected from the respective ejection nozzles.
Moreover, regarding the regular ink jet printer, there is conventionally known a technology of performing a printing operation by using only a part of a nozzle array including continuously arranged normal ejection nozzles when any of the ejection nozzles are determined to be abnormal.
When the ejection confirming operation for the function liquid is performed by using such optical liquid droplet detection means as that of the foregoing conventional example, which includes the emitting element and the light receiving element, an erroneous determination is sometimes made. Specifically, even if the function liquid is normally ejected from the ejection nozzles, a determination of abnormal ejection is made, that is, the ejection nozzles may be determined to be abnormal due to satellite (floating misty particles resulting from an ejected liquid), electrical noise and the like.
Moreover, if an imaging operation is performed by using only a part of the nozzle array including the continuously arranged normal ejection nozzles, as described in the foregoing conventional example, when any of the ejection nozzles are abnormal, the operation takes long and efficiency is lowered. Here, even if the function liquid is not normally ejected, execution of the maintenance operation, such as the preliminary ejection of ejecting the function liquid from the ejection nozzles, may sometimes restore a state where the function liquid is normally ejected.